The term 'Makes Less Dense' can be solved by two crossword solutions, 'Thins' (5 letters) and 'Rarefies' (8 letters). Both words refer to the process of making something less dense or more spread out. Thinning is a process of reducing the concentration of something, while rarefying is the process of making something less dense or more spread out. Both terms are used in a variety of contexts, from cooking to physics.